Tube drawing apparatus



Feb. 17, 1959 D. L. LOMBARD TUBE DRAWING APPARATUS 5 Sheets-Sheet 1 Filed May 14, 1956 INVENTOR Daniel L.Lombqrd W ATTORNEY 1959 V D. L. LOMBARD 2,873,849

TUBE DRAWING APPARATUS Filed May 14, 1956 5 Sheets-Sheet 2 F Fig.4 I l I 50 r \l i l Feb. 17, 1959 5 Sheets-Sheet 3 Filed May 14, 1956 Fig.5

iii" 5 Sheefs-Sheet 4 D. L. LOMBARD TUBE DRAWING APPARATUS Feb. 17, 1959 Filed May 14, 1956 Feb. 17, 1959 n. LOMBARD 2,873,849

TUBE DRAWING APPARATUS Filed May 14, 1956 s Sheets-She et 5 Fig.8

' invention;

TUBE DRAWING APPARATUS Daniel L. Lombard, Youngstown, Ohio, assignor to Lombard Corporation, Youngstown, Ohio, a corporation of Ohio Application May 14, 1956, Serial No. 584,564

3 Claims. (Cl. 205-3 This invention relates to draw carriages for pulling tubes and the like through a die, and more particularly 'eration a reduced-diameter tube end is passed through a die and engaged by gripper jaws carriedon a draw car- .riage or dolly which travels on a track extending parallel to the central axis of the die. gagesone or more continuously moving chains which This draw carriage enforce it along its track outwardly and-away from the die, thereby pulling the tube through the die.'

M It is a common occurrence in the drawing of tubes for thesame to jump forwardly with considerable force as .the trailing ends thereof pass through the dies, the ob- ,viousreason being that the tubes are under substantial tension during the drawing operation and-the sudden release of such tension is accompanied by a release of energy which propels the tubes forwardly with consider- .able force. This is a serious problem in that the forward ends of the tubes are driven. against the draw carriage so that often they are rendered unsuitable fora ,subsequent drawing operation, or partially so. It is an object of this invention to provide means in a draw carriage for preventing damage to the forward .ends of newly-drawn tubes when they jump forwardly at the completion of a draw.

A further object of the invention resides in the pro- .visionof means in a drawbench which willdefiect newly dr a wn-tubes into a receiving bin 'orthe like at the completion vof a drawing operation.

United Sums, Pathto" 2,873,849 Patented Feb. 17, 1959 ent invention; Y

Fig. 8 is a sectional view, similar to that of Fig. 6, of a modification of the invention;

Fig. 9 is a sectional view taken along line IX--IX of Fig. 8; and

Fig. 10 is a view of the same section as that of Fig. 8 showing the location of the various elements of the gripper mechanism of the draw carriage at the completion of a draw.

Referring to Figures 1-3, the numeral 10 represents generally the main framework of a drawbench assembly which is comprised of aplurality of spaced frame sections 12, as shown in Fig. 3. may be fabricated or ordinary structural members welded or otherwise securely fastened together. Each section includes an upright member 14 and a horizontally disposed cantilever beam 16 extending outwardly from: the upright member or post 14. Depending downwardly from the outer end of the cantilever beam 16 is a short beam section 18, which carries at its lower end a track support 20. The support 20 is one of a complementary pair, a second support 22 being carried by the post '14, as shown.

As will be understood, the complete drawbench assembly incorporates a plurality of frame sections 12, mounted in spaced relation along the length of the drawbench. Carried by the supports 20 and 22 of such sections are spaced tracks 24 and 26 which may, for example, be elongated sections of angle iron. The tracks 24 and 26 support a draw carriage 28 against gravity and guide it in longitudinal movement throughoutthe length of the drawbench, as will be subsequently developed herein. Adjacent and slightlybelow each of the track supports 24 and 26 are guidingand supporting channels 30 and 32 for a pair of spaced draw chains 34 and 36 which are employed to draw the carriage 28 along the tracks 24 and 26 during a drawing operation. Supported in depending relation from the cantilever member 16 is another channel 38 which supports and guidesa 'third chain 40 which is utilized in the illustrated apparatus as a return chain for returning the carriage 28 to its initial position immediately following a-drawing operation; it

In accordance with preferred practice, the main draw chains 34 and 36 are endless and rotate continuously in one direction. Therefore, suitable sprocket wheels 42 are provided at each end of the respective traverses of A.still further object of the invention is to provide means for absorbing the kinetic energy-of rapidly moving tubes after they are directed into a receiving bin or I ,The above and other objects'and features of the inthe like by a deflector carried on a draw carriage.

vention will become apparent from the following detaileddescription'taken in, connection with the accompanyingdrawings which form a part of this specification and in which:

Figurel is a side elevation of a drawbench assembly with which the present invention may be used;

Fig. 2 is a top view of the apparatus shown in Fig. 1; Fig. 3 is a sectional view taken along the line IIII Y 'of Fig. 1;

Fig. 4 is a sectional view of the die block of the drawbench shown in Figs. 1 and 2;

. .Fig. 5 is a top view of the draw carriage of the present or return reaches of the drive chains may be the chains 34.and 36, and additional guiding and supporting channels 30' and 32' (Figure 3) aresupported on the lower portions of sections 12 so that the lower properly supported.

At the right-hand end of the drawbench assembly there i is provided a heavy duty drive motor'44 and gear reducer 46, the latter of which has driving connection with the chains 34 and 36 for effecting synchronous movement thereofin the manner desired. In the illustrated embodiment there is also provided a smaller drive motor 48 having driving connection with the return chain 40. The motor 48 is preferably energized only upon completion of a drawing operation, being maintained in an inoperative condition throughout the duration of an actual drawing operation.

' At the left end of the mainframe 10 of the drawbench 10 is a die block 50, shown in detail in Figure -4. The

die block comprises a main shank portion having a plurality of spaced'die assemblies extending therethrough. Each die assembly comprises a die cup 52 having a generally spherical end which fits into a c ooperating cup formed in die block 50. Thedie 53 is carried within the die cup The frame sections 12.

52- and is held therein by -as--shown. In the drawing operation, a plurality of tubes a die cup nut 55, substantially 57 are drawn through these dies by the draw carriage 28.

Extending to the left of the die block 50 is an elongated mandrel supporting table 5 5 which has means 56at its extreme left end foranchoring and manipulating a plurality of mandrel rods 58 corresponding in number to the number of dies 52. Each of the mandrel rods has an enlarged head at its extreme right end which is inserted into a corresponding die during a drawing operation.

'In conventional tube drawing practice, a plurality of tubeblanks are first passed over the plurality of mandrels 58,-which are then inserted into the openings in the dies 52. The leading ends of the blanks are gripped by the draw carriage 28 which, when moved away from the die block 50, carries the tube blanks along with it. The

blanks'are-thereby reduced to the dimensions of the annular opening between the inner periphery of a die and .theouter periphery of the enlarged head of the mandrel which extends into the die.

Tofacilitate loading of the tube blanks onto the mandrel rods 58, there is provided above the main frame a rack orplatform 60 which supports a plurality of blanks, not shown, arranged generally in end-to-end relationship .with respect to the rods 58. Suitable means, not shown, areprovided for elevating the enlarged ends of the mandrel rods and for sliding the blanks over these enlarged ends during a loading operation. An operators platform 62 is provided adjacent the die block 50.

Referring to Figs. 57, the draw carriage ofthe present invention comprises a rigid frame 64 including rigid side members 66. The draw carriage is provided with four supporting wheels or rollers 68 to facilitate horizontal movement and four guiding wheels 70 rotating about vertical axes. The wheels 68 and 70 are adapted to engage the horizontal and vertical surfaces, respectively, of the guiding and supporting tracks 24 and 26 whereby the carriage 28 may have free guided movement throughout the-length of the main frame 10 of the drawbench.

At the bottom of the rigid side members 66 shown in Fig. 5 are machined a pair of keys 72 and 74 which fit into cooperating keyways in a gripper head 76. The gripper head comprises a heavy block of steel having formed therein a plurality of forwardly converging guide slots 7 8 adapted for the reception of stock-engaging grip bits 80 and 82, the arrangement being such that upon forward movement of the hits the same are caused to converge while upon rearward movement they are caused to diverge. The guide slots 78 are open at the lower side of the gripper head 76, there being a plurality of spaced plates 84 (Figs. 6 and 7) provided to partially. enclose the openings thus formed and retain the grip bits 80 and 82 therein. Each of the bits 80 and 82 is provided with a transverse slot 86 in its upper surface for the reception elftransverse arm portions of a slide block 88 which is guided for longitudinal movement on the spaced plates 84. Upon forward movement, for example, of the slide block 88, its associated grip bits will be caused to converge.

To actuate each of the slideblocks, there is provided an arrangement including longitudinally movable pistons or plungers 90 which abut against the back surfaces of the slide blocks 88. The pistons 90 are received for reciprocating movement within bores or cylinders 94 carried by a metal transversely-extending block 95. A transversely extending passage 98 is provided in the block 95 for conducting compressed air into the respective cylinders 94. Upon the introduction of compressed air into cylinders 94, pistons 90 will be forced to the left as shown in Fig. 6, thereby causing the grip bits 80 and 82 associated with each piston to converge.

At the extreme right end of each of the cylinders 94 is placed a pre-loaded hydraulic shock absorber 100. An impact on plunger 102 of shock absorber 100 will compress the fluid contained within the shock absorber to thereby absorbthe kinetic energy of a moving object.

"by -grip bitsand--82will force slide blocks 88 and pistons back against the plungers 102 of shock a bsorbers which dissipate the forward kinetic energy of the blanks and slide block assemblies. In the retracting stroke grip bits 80 and 82 diverge and allow the blanks to drop out through the lower openings of the guide slots 78.

In order to effectively carry out drawing operations in the manner described above, it is necessary that the area below the draw carriage 28 be open so that upon discharge of the drawn tubes from the lower side of the carriage the tubesmay fall freely into a receiving bin or the like. It has been found most practical to drive the draw carriage from opposite sides, leaving the bottom area entirely clear. Accordingly, the drive chains 34 and 36 are positioned immediately below and adjacent the side edges of the carriage 28, as shown in Fig. 3. In the illustrated apparatus there is provided a receiving rack 104, extending along the front side of the drawbench frame 10, in which the finished tubes are-deposited following a drawing operation. The rack 104 is positioned in ofiset relation with respect tothe draw carriage 28 to facilitate unloading of the finished tubes. A sloping run out table 106 is located directly below the carriage to receive the tubes as they drop and to direct the same into the receiving rack 10 It will be understood that the sudden release of energy bythe tubes as they-leave their associated dies will cause them to jump forwardly with considerable force against slide blocks 88. In tubes having a relatively small diameter there is a possibility of bending or otherwise damaging the ends of the tubes when they strike the slide blocks. Inorder to insure against this possibility an inclined groove 108 is provided on the underside of each of the slide blocks so that the newly drawn tubes will be deflected downwardly out through the lower openings of the guide'slots 78 and onto run out table 106. When the tubes strike inclined grooves 108, pistons 90 will move to the right, and part of the energy of the tubes will be absorbed by shock absorbers 100. A T-section member 110 extending between rigid side members 66 prevents slide blocks 88 from moving upwardly when the tubes strike inclined grooves 108. The impact of the tubes against the backs of grooves 108, however, will not be great enough to damage their forward ends since part of their kinetic energy is retained as they are deflected downwardly. It has been found in actual practice that when an inclined surface of this sort is employed, the deflected tubes will bolt ahead under the drawcarriage at a very high rate of speed and will strike a back board at the remote end of run out table 106 and receiving rack 104. A tube moving at a high rate of speed after being released by grip bits 80 and 82 may buckle or spring and cause damage to itself or the draw bench frame 10 and its associated parts. Actually, the behavior of a long slender tube moving at a high rate of speed is diflicult to predict, so it is altogether desirable to provide means for impeding the forward movement of the tubes immediately after they are deflected downwardly by inclined grooves 108.

To impede the forward movement of the tubes under the drawcarriage, a series of downwardly extending bafile plates or the like 112-116 are pivotally connected between the rigid side members 66 of the drawcarriage. The plates 112116 may be fabricated from rubber, metal, fabric or any other suitable material which is best adapted for a particular application. In the embodiment of the invention shown herein, there are three separate plates for each die 53 and set of grip bits 80 and 82. The plates 112 -116 are suspended from shafts 118 which are, in turn, supported by rigid side members 66. Suitable spaces 119 separate the respective plates, on each shaft as shown in Fig. 7. As will be understood, the rapidly moving tubes, after being released by grip bits 80 and 82 will strike the balfle plates 112116 which partially impede their forward movement and insure against damage to the frame or to the tubes themselves.

To engage the carriage 28 with the chains 34 and 36 for effecting a drawing operation there is provided a pair of retractable, chain-engaging hooks 120 which are mounted at opposite sides of the carriage 28. The hooks 120 are normally urged upwardly into a retracted position; while air-operated plunger assemblies, not shown, carried within, the housings 122 are adapted to move the hooks downwardly into an extended or chainengaging position. It is to be understood, of course, that shown in Fig. 8.

The position of the various elements during the period that the tubes are being drawn and are in tension is Grip bits 80 and 82, slide block 88,

' and piston 90 are all forced to the right by air pressure the drive chains 34 and 36 are driven continuously'and sate for such unbalance.

In order to prevent a condition of unbalance, the' hooks 120 are mounted on slidable block assemblies124 and 126 which are received in slots 128 in the carriage side members 66 and adapted for limited longitudinal sliding movement with respect thereto. An equalizer or draw bar 130 is mounted for pivotal movement about a centrally located vertical axis 132. As shown in Fig. 5, the forwardly extending portions 130' of the draw bar are positioned outwardly with respect to the side members 66 and are adapted to abut the rear end faces of the hook mounting assemblies 124 and 126. Normally, the assemblies 124 and 126 are drawn back against the draw bar 130 by means of suitable springs 131 and 133. When the hooks 120 are forced downward to engage the draw chains 34. and 36, and one hook engages before the other, the first-engaged hook will begin to move relative to the carriage; and as it does so it will cause the draw bar 138 to pivot about its axis 132, moving the other hook in the opposite direction relative to the carriage until such hook finally engages itsassociated drive chain. At this time both hook assemblies 124 and 126 are drawn tightly against the draw bar. Drawing forces are in this manner transmitted through the bar to the carriage. Thus, any out-of-phase relationship of the draw chains 34 and 36 is compensated for by relative longitudinal movement between the hook assemblies 124 and 126; and, consequently, unbalanced forces and other undesirable effects are wholly avoided.-

Another embodiment of the draw carriage of the present invention is shown in Figures 8, 9 and 10. The main body of the draw carriage is substantially the same as that shown in Figs. 5-7; and, accordingly, elements in Figs. 8-10 corresponding to those in Figs. 5-7 are indicated by-like reference numerals.

In the modification of the invention shown in Figs. 8-10 there is machined a transversely-extending slot 134 in the lower portion of the rear face of gripper head 76. In the area between each of the grip bits 81) and 82 is machined a slot 136 which extends from slot 134 to the bottom surface of the gripper head 76. A series of T-shaped gate members 138, each having a flat shank portion 140, have their upper cross bars 142 machined to form a circular cross section; and these cross bars are inserted into slot 134 in a manner such that the shank portions 140'extend down through slots 136 into the area defined between grip bits 80 and 82. A transversely-extending plate 144, fastened to the rear surface of gripper head 76 by bolts 146' has a lip 149 which extends over slot 134 to hold the cross bars 142 within the slot while permitting independent rotationof each of the bars 142 and its associated shank portion 140. On the lower frontal edge of each of the slide blocks 88 is an inclined surface 150.

in' cylinder 94 or tension on the grip bits, as the case may be. Each of the shank portions 140 extends vertical- 1y downward between its associated grip bits 80 and 82,

substantially as shown. When a tube snaps free of its die at the completion of a draw, grip bits 80 and 82,

slide block 88 and piston 90 will be forced to the right against plunger 102 of shock absorber 100, as shown in Fig. 10. As the grip bits move to the right, they will diverge and release the forward end of the drawn tube which, due to its kinetic energy, will then bolt forward and strike shank portion 140, causing it to rotate in a counter-clockwise path until it strikes the inclined surface 151} on slide block 88. As will be understood the arrangement is such that when the shank portion 140 is rotated about the central axis of cross bar 142 into the position shown in Fig.10, the end of the newly-drawn tube will slide down the inclined shank and will strike battle plates 112-116 before dropping onto runout table 106. As was the case with the configuration shown in Figs. 5 7, part of thekinetic energy, of the tube is absorbed by shock absorber 100.

In the operation of both of the embodiments of th invention, a plurality of tube blanks or workpieces are first loaded onto the mandrels 58, and swaged or reduced diameter ends of the workpieces are inserted through the die openings. Next, the draw'carriage 28 is moved up to the die block 50 by return chain 40 which engages a member 148 on the carriage (see Fig. 5). When the carriage 28 is in its extreme left position shown in Figs. 1 and 2 and the grip bits extend over the reduced diameter portions of the tube blanks, suitable means, not shown, will admit compressed air through passage 98 into cylinders 94, the arrangement being such that pistons 90, slide blocks 88, and grip bits and 82 will be forced forward into gripping position.

After the grip bits engage the ends of the tubeblanks, the hooks 120 are moved downward into a chain-engaging position, and the carriage 28 begins to move to the right as shown in Figs. 1. and 2, thereby initiating the drawing operation. At this time the air pressure on pistons is released. However, it will be observed that the application of drawing force by thegrip bits wand Figs. 1 and 2 the tube blanks will snap free of the dies 52 and will be deflected downwardly by inclined grooves 108 or gate members 138, as the case may be, where bafiie plates 112-116 will impede their forward movement in the manner described above.

Although the invention has been described in connection with a certain specific embodiment, it should be readily apparent to those skilled in the art that various changes in form and arrangement of parts of the apparatus may be made to suit requirements without departing from the spirit and scope of the invention.

I claim as my invention:

1. In a drawbench adapted to draw tubes and the like through a die and including a track extending parallel to the central axis of said die on one side thereof, the combination -of a draw carriage movable along said track, said draw carriage having a main body portion supported on said track by anti-friction elements, gripper jaws supported on one end of said draw carriage and movable relative thereto between gripping and retracted positions, a member located behind said gripp j an inclined surface located on said member behind the forward end of a tube engaged by said gripper jaws for deflecting a tube below the body of said draw carriage at the completion of a draw when the gripper jaws release said tubes, and a, plurality of baffle plates pivotally supported on the bottom of said body portion for impeding the forward motion of a tube after it is-deflected below the body by said inclined surface.

2. In a drawbench adapted to draw tubes and the like through a die and including a track extending parallel to the central axis of said die on one side thereof, the combination of a draw carriage movable along said track, said draw carriage having a main body portion supported on said track by anti-friction members, tube gripping means located at one end of said body portion, an inclined surface located behind said gripping means and beyond the forward end of a tube engaged by said gripping means for deflecting the tube below the body of said draw carriage at the completion of a draw when said gripping means releases the tube, and a plurality of baffle plates pivotally supported on the bottom of said body portion for impeding the forward motion of a tube after it is deflected below the body by said inclined surface.

3. In a drawbench adapted to draw tubes and the like through a die along a path defined by the central axis of said die and including a track extending parallel to the central axis of said die on one side thereof, the combination of a draw carriage movable along said track, tube grippin'gmeans carried by said draw carriage at one end thereof, means located beyond the forward end of a tube engaged by said gripping means for deflecting the tube out of the path defined by the central axis of saiddie, and a plurality of baffles pivotally car ried by said draw carriage for impeding the forward motion of a tube after it is deflected by said means for defleeting.

References Cited in the file of this patent UNITED STATES PATENTS 2,161,471 Hueglin June 6, 1939 2,275,573 Strum et al. Mar. 10, 1942 2,554,998 Mcllvried et a1 May 29, 1951 FOREIGN PATENTS 138,202 Australia Aug. 4, 1950 595,470 Great Britain Dec. 5, 1947 707,206 Great Britain Apr. 14, 1954 

